I2C Communications with DSP proc and DAC

I am using an arduino to control an upgraded DAC in a cd player and I am using I2C.

Some times I write and read the proper data and get 0 for ACK from Wire.endTransmission();
But there are other times when it doesn’t send and receive the proper data. The code I have just loops naturally with a delay long enough for me to read whats returned.

There is a 16.3944Mhz crystal between the DSP and the DAC. Does the arduino need to be synced to that some how so that all three systems are connected?

Or are I2C communications separate from everything else in the DAC?

Or are I2C communications separate from everything else in the DAC?

Yes.

Have you put pull up resistors on the I2C lines. Use 3K3 as the internal pull ups in the arduino are a bit weak.

I did but I just used some 1k resistors (i think), might be lower. I just used what was handy on the desk at the time. Ill try some larger ones and see if that helps.

Thanks for the suggestion.

Some times I write and read the proper data and get 0 for ACK from Wire.endTransmission(); But there are other times when it doesn't send and receive the proper data.

How is your decoupling:- http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

Decoupling is good. I am using a TI app note as initial reference just to get it working. I am using a 10uf lytic and a .047 film for all the supplies on the DAC (5 of them)

I am also using the arduino for 5v and 3.3v supply so that could have something to do with it also?

It could be the IC itself too. I forgot some grounds on the analog side and the IC got really hot so im going to try a new one (#4, its a learning experience lol).

I am an EE student but this is beyond anything we have learning thus far so this is a learning experience for me as progress in the project.

thanks for the help